Biology and Fertility of Soils

, Volume 43, Issue 6, pp 699–708

Biological nitrogen fixation by common beans (Phaseolus vulgaris L.) increases with bio-char additions


    • Centro Internacional de Agricultura Tropical (CIAT)
    • International Development Research Centre
  • Johannes Lehmann
    • Department of Crop and Soil SciencesCornell University
  • Juan Ramírez
    • Centro Internacional de Agricultura Tropical (CIAT)
  • Maria Hurtado
    • Centro Internacional de Agricultura Tropical (CIAT)
Original Paper

DOI: 10.1007/s00374-006-0152-z

Cite this article as:
Rondon, M.A., Lehmann, J., Ramírez, J. et al. Biol Fertil Soils (2007) 43: 699. doi:10.1007/s00374-006-0152-z


This study examines the potential, magnitude, and causes of enhanced biological N2 fixation (BNF) by common beans (Phaseolus vulgaris L.) through bio-char additions (charcoal, biomass-derived black carbon). Bio-char was added at 0, 30, 60, and 90 g kg−1 soil, and BNF was determined using the isotope dilution method after adding 15N-enriched ammonium sulfate to a Typic Haplustox cropped to a potentially nodulating bean variety (CIAT BAT 477) in comparison to its non-nodulating isoline (BAT 477NN), both inoculated with effective Rhizobium strains. The proportion of fixed N increased from 50% without bio-char additions to 72% with 90 g kg−1 bio-char added. While total N derived from the atmosphere (NdfA) significantly increased by 49 and 78% with 30 and 60 g kg−1 bio-char added to soil, respectively, NdfA decreased to 30% above the control with 90 g kg−1 due to low total biomass production and N uptake. The primary reason for the higher BNF with bio-char additions was the greater B and Mo availability, whereas greater K, Ca, and P availability, as well as higher pH and lower N availability and Al saturation, may have contributed to a lesser extent. Enhanced mycorrhizal infections of roots were not found to contribute to better nutrient uptake and BNF. Bean yield increased by 46% and biomass production by 39% over the control at 90 and 60 g kg−1 bio-char, respectively. However, biomass production and total N uptake decreased when bio-char applications were increased to 90 g kg−1. Soil N uptake by N-fixing beans decreased by 14, 17, and 50% when 30, 60, and 90 g kg−1 bio-char were added to soil, whereas the C/N ratios increased from 16 to 23.7, 28, and 35, respectively. Results demonstrate the potential of bio-char applications to improve N input into agroecosystems while pointing out the needs for long-term field studies to better understand the effects of bio-char on BNF.


Biological N fixationBoronCharcoalMolybdenumMycorrhiza15N

Copyright information

© Springer-Verlag 2006